We are not aware of any other blogs or news websites that have a strong focus on recommender systems. Besides RS_c, your best option for news relating to recommender systems is probably Twitter and the hashtag #recsys, and for a more academic focus creating alerts and conducting regular searches on Google Scholar, SemanticScholar, ResearchGate, and arxiv.org. It might also be worth visiting the Blog of the ACM Recommender Systems Conference once in a while. Though, it is not very active.
If you know any blogs, news websites, and portals that specialize in recommender systems, please let us know.